A wide variety of materials have been used to treat or dress different types or kinds of wounds. Typical materials that are used in the various dressings include wound contact materials and absorbent materials as well as compressive materials which are used to hold the wound contact and absorbent materials in place and which provide compressive force to the wound. For example, chronic wounds such as venous stasis ulcers have commonly been treated or dressed by wrapping as many as four separate layers each of a different type of material around the leg. Specifically, a four layer bandage developed at Charing Cross Hospital, London, includes an inner exudate absorbent layer (VELBRAND wrap, Johnson & Johnson, New Brunswick, N.J.), a crepe bandage, a compressive bandage (ELSET bandage, Seton) and an elastomeric wrap (COBAN self-adherent elastomeric bandage, 3M, St. Paul, Minn.). The use of multiple layers of different materials adds considerable time and expense both to the dressing itself and to the process of applying and changing the dressing.
Elastic fabric wraps are often used as an outer layer of compression wound dressings in order to hold the inner layers in place and to apply compression to the wound. The use of fabric elastomeric wraps, however, is not always desirable because dressings wrapped with elastic fabrics are likely to slip or shift after being applied which may result in insufficient compression being applied to the wound by the dressing or which may cause discomfort to the patient. Attempts to overcome the problems of slipping or shifting include applying a hydrocolloid adhesive to one side of the fabric wrap. The hydrocolloid adhesive is intended to stick to skin in order to prevent slippage (a bandage of this type is commercially available and is sold as DUODERM adhesive compression bandage, ConvaTec, Princeton, N.J.). Furthermore, many elastic fabrics do not have the capability of absorbing fluids.
In addition to the elastic fabric bandages referred to above, a variety of other wound dressings or bandage materials have been reported. A elastomeric self-adhering bandage is reported in U.S. Pat. Nos. 3,575,782 to Hansen and 4,984,584 to Hansen et al. According to the disclosure of these patents, elastic yarns are bonded between two layers of a nonwoven web with latex rubber to provide a bandage having good compression characteristics and cohesiveness or the ability to self adhere. The reported elastic bandage, however, does not have the capability of absorbing fluids and therefore could not be used alone as a satisfactory wound dressing. Another elastic self-adhesive, cohesive bandage is reported in U.S. Pat. No. 4,699,133 to Schafer et al. The Schafer et al. bandage is reported to provide permanent elastic compression by use of elastic threads in a woven fabric which is coated with self-adhering particles. The Schafer et al. bandage also does not have the capability of absorbing fluids.
Another type of elastic material is reported in U.S. Pat. No. 4,707,398 to Boggs that discloses an elastomeric nonwoven web that is formed from meltblown fibers. The nonwoven web is reported to be an absorbent material but is not reported to be self-adhering. Other nonwoven elastic web materials are reported in U.S. Pat. Nos. 4,663,220 to Wisneski et al., 4,720,415 to Vander Wielen et al., 4,789,699 to Kieffer, and 5,230,701 to Meyer et al. An absorbent nonwoven material is reported in U.S. Pat. No. 4,957,795 to Riedel. The Riedel material is reported to be a web of elastomeric melt-blown fibers and absorbent fibers dispersed in a nonwoven matrix. A wound dressing having a fluid permeable wound contact layer, the melt-blown absorbent layer and a soft compliant cover layer is also disclosed.
Yet another type of wound dressing material is reported in U.K. Patent 1 575 830 that discloses an absorbent dressing having an absorbent layer laminated to a plastic backing film. The backing film is reported to be a flexible, easily stretchable film but is not self-adhering.
A need exists for a unitary wound dressing which retains exudate and is self-adhering, absorbent, flexible and conformable, as well as capable of maintaining a therapeutic compressive force at the wound site for extended periods of time. In addition, a desired wound dressing should have the capability of being easy to apply and remove as well as being easily repositioned or rewrapped without losing any of the other desirable properties listed above.